Juha Saari

Loss Minimization for Form-Wound Stator Winding of a High-Speed Induction Motor

Resistive losses in the form-wound stator winding of a high-speed induction motor (HSIM) are minimized in the design stage by using Differential Evolution (DE). Time-discretized finite-element analysis (FEA) serves as a tool to offer electromagnetic losses in the machine for the optimization process. Temperature rise of the machines is fast checked during the optimization by using a thermal network model. Insulation thicknesses and power factor are other constraints in the algorithm. Time consumption of using time-discretized FEA is still a problem when a large number of variables or motor dimensions is required for the optimization algorithm. To reduce the number of required variables, the influence of stator dimensions on the electromagnetic losses is analyzed by using the Taguchi approach. From this evaluation, the important stator parameters to be varied during optimization algorithm are determined. Finally, form-wound stator winding with a minimum loss for a HSIM is obtained within certain limitations.

Form-wound stator winding for high-speed induction motors

Random-wound stator windings of high-speed induction motors (HSIM) have serious problems with eddy-current losses because their circular copper wires are randomly distributed. As a result, the differences in the total electromotive forces induced in the parallel conductors cause high additional losses in random-wound windings. Moreover, the eddy-current losses are underestimated during design stage due to difficulties of modeling eddy-current effect in the random-wound windings. A form-wound stator winding is an alternative option to reduce those losses. A roughly designed model of form-wound winding is presented based on the original random-wound stator windings of HSIM. Time-discretized finite-element analysis (FEA) is used to model losses in a 300 kW HSIM with random and form-wound stator windings. Those losses are used as the input data for the temperature rise analysis to check temperature rise constraints of the designed machine. Possibilities using form-wound windings for HSIM are evaluated from the losses and temperature rise analysis.